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( Article Type: Explanation )

Dilution in the context of environmental management describes a strategy to deal with pollution. Certain liquid effluents are, for example, disposed of down sewers by being heavily diluted with clean or relatively clean water. This used to be a cost effective waste management solution when water costs were very low (i.e. a subeconomic price which did not relate to the cost of supplying the quantities and qualities of water).

However, the new National Water Act has dictated that water prices will be more economically related and, as a result, the use of potable water as a dilutant becomes prohibitive and alternatives must thus be sought. This strategy forces industry to look for alternatives, which often include either reducing or eliminating the effluent in the first place. It is also possible to ‘dilute’ chimneystack emissions by adding air or burning gases to dilute concentrated emissions.

The current weak South African air pollution legislation means that there are no strong controls or pressures regarding the dilution of air emissions. (It could be argued that, in some cases, dilution of particular air emissions makes little difference to the health or environmental impacts of the gases and particulates.)

However, the current air pollution legislation is now in the process of being rewritten and the new regulations will be stricter, echoing the strategies of the water legislation.